No effect of salmon fish protein on 2-h glucose in adults with increased risk of type 2 diabetes: a randomised controlled trial

Abstract

The association between fish consumption and decreased risk of CVD is well-documented. However, studies on health effects of fish consumption, suggest that other components than omega-3 polyunsaturated fatty acids have beneficial cardiometabolic effects, including effects on glucose metabolism. The aim of the present study was to investigate effects of salmon fish protein on cardiometabolic risk markers in a double-blind, randomised controlled parallel trial. We hypothesised that daily intake of a salmon fish protein supplement for eight weeks would improve glucose tolerance in persons with increased risk of type 2 diabetes mellitus. Our primary outcome measure was serum glucose (s-glucose) two hours after a standardized oral glucose tolerance test (OGTT). In total, 88 adults with elevated s-glucose levels were randomised to 7.5 g salmon fish protein/day or placebo, and 74 participants were included in the analysis. We found no significant effect of salmon fish protein supplementation on our primary outcome or other markers related to glucose tolerance, serum lipids, weight or blood pressure compared to placebo. The present study does not support the hypothesis that daily intake of a salmon fish protein supplement for eight weeks improves glucose tolerance in persons with increased risk of type 2 diabetes mellitus. The study was registered at ClinicalTrials.gov (ID: NCT03764423).

Salmon fish protein supplement increases serum vitamin B12 and selenium concentrations: secondary analysis of a randomised controlled trial

“…In the previously mentioned RCT comparing intake of salmon or cod consumed as whole filet (750 g/week), only cod increased s-selenium compared to controls [ 29 ]. We have previously performed a post-prandial analysis of serum amino acids in five healthy adults after intake of the study product, and found a non-significant increase in serum levels of most amino acids [ 15 ], supporting that the capsules were absorbed. Both B12 and selenium have high bioavailability and serum and plasma concentrations reflects dietary exposure [ 7 , 30 ], supporting our findings in the present study.…”

“…Thus, 76 participants completed the study. Two participants were non-compliant with the study protocol, leaving a total of 74 participants included in the statistical analysis, as previously reported [ 15 ]. The participants were 56 (Q1–Q3: 48–64) years of age, with a BMI of 33.1 (Q1–Q3: 29.9–36.1) kg/m 2 and 64% were female.…”

“…The present study is based on a previously performed randomised controlled trial, the FishMeal human intervention study, where the primary outcome was changes from baseline in serum glucose (s-glucose) measured after a 2-h oral glucose tolerance test (OGTT). The description of participants, study setting and protocol for study visits have been published in detail previously [ 15 ]. In brief, the study was conducted at the University of Oslo, Norway from August 2018 until September 2019.…”

“…Compliance was assessed by counting the number of capsules consumed during the intervention period, divided by the number of capsules scheduled for the intervention period. All participants had a compliance > 70% [ 15 ]. We advised the participants to maintain their usual lifestyle habits throughout the study, including physical activity, supplement use and diet, except for a reduction in fish and seafood intake to a maximum of 150 g per week.…”

“…We have previously reported the effects of eight weeks of daily intake of a fish protein supplement made from by-products from production of Atlantic salmon on cardiometabolic risk markers in adults with increased risk of type 2 diabetes mellitus. We found no beneficial effect on markers related to glucose tolerance, serum lipids, weight or blood pressure compared to the placebo group [ 15 ]. In the present secondary analysis, the main aim was to examine the effect on blood concentration of micronutrients related to fish intake or abundant in fish by-products.…”